Hi, I just came across this thread on LastPass forum in which the thread starter identified CCleaner as the culprit behind LastPass's problem. Israel, who is a LastPass developer, appears unsurprised and even criticized CCleaner developers for failing to respond to their request. The other user advise the thread starter not to use CCleaner which is in my opinion is a bad advice.
I'm running LP and CCleaner and I don't encounter the issue the thread starter described, but I do have concerns and this is something you might want to take a look into.